Area Forecast Discussion
Issued by NWS Twin Cities, MN

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000
FXUS63 KMPX 181743
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1243 PM CDT Mon Mar 18 2024

.KEY MESSAGES...

- Elevated fire weather conditions persist through the middle of
  the work week (peaking on Tuesday).

- Gusty northwest winds return Tuesday, with gusts up to 40 mph
  possible.

- Confidence is increasing in the potential for accumulating
  snow across the region Thursday.

- Active pattern sets up for the weekend and early next week.

&&

.DISCUSSION...
Issued at 332 AM CDT Mon Mar 18 2024

It`s another brisk night with northwest winds still sustained
10 to 15 mph but the gustiness has tapered off. Temperatures are
currently in the upper teens and low 20s across Minnesota and
western Wisconsin. Wind chills are in the single digits
everywhere but the core of the Twin Cities metro and serves as a
pleasant reminder than cold and wintry weather conditions are
still possible in March & April. A stratocu layer is present
over the region and like last night is producing areas of
flurries & very light snow showers. This cloud layer will
scatter out after sunrise, but we`re going to have a broken mid-
level deck building in this afternoon to replace it.
Temperatures will warm into the mid to upper 30s and winds will
shift from the northwest to the west and eventually southwest
tonight.

The driving force behind the wind shift is a quick moving
clipper system that will track along the international border
before dropping into the northern Great Lakes region on Tuesday.
Tuesday still looks like the warmest day this week with highs
in the mid 40s. This clipper will bring the thermal ridge &
associated sfc front through Monday night. The timing of this
means we`ll likely trend a few degrees colder with our highs on
Tuesday since we`ll be in cold air advection after sunrise
Tuesday. Winds will turn back to the northwest Tuesday morning
and the gustiness will return Tuesday afternoon. Winds will be
sustained 20 to 25 mph with gusts up to 40 mph making it feel
similar to this past weekend. With forecast winds near advisory
level, attention will turn back to fire weather concerns. The
strong winds, low minimum RH`s, and very dry fuels will lead to
elevated fire weather concerns Monday through Wednesday. We`ll
see fire weather concerns peak Tuesday. Our cold advection will
flip the temperatures back to the cold side of things for
Wednesday, with below normal highs back in the low 30s.

An active pattern is set to return for the second half of the
week. You knew it had to snow again eventually... right? There
is always a level of uncertainty with any system that`s still
over 96 hours out but forecast confidence is beginning to
increase due to the consistency across guidance. A mid-level
shortwave will extend eastward across the Upper Midwest Thursday
into Friday. Warm air advection will increase ahead of the
system across the Northern Plains and Upper Midwest on Thursday.
This WAA will lead to a broad area of isentropic ascent tied to
a weak warm front that will lead to the development of a
northwest to southeast oriented band of light snow across the
Dakotas that`ll track into Minnesota and Wisconsin Thursday
afternoon. There is still a vague signal for the potential of an
embedded band of heavier snow driven by low level frontogenesis
that we`ll have to keep an eye out for once hi-res guidance
gets into range. Conceptually, guidance has an impressive
temperature gradient at 850mb associated with the weak low level
warm front. This feature is present at 700mb, too but is
displaced to the northeast of the 850mb gradient. Conceptually,
it should lead to a narrow band of heavier snowfall driven by an
FGEN circulation. Unfortunately, these features aren`t easy to
pick up until hi-res guidance is available, which would be
Tuesday night & Wednesday, so until then we`ll focus on the
broad snow & the associated impacts from that. Ensemble mean QPF
has trended up since last night`s 00z runs across all of the
major ensemble systems (EPS/GEFS/GEPS). They highlight a broad
band of 0.20 to 0.30" QPF across MN & W WI by Friday morning.
The 00z ECMWF QPF has trended higher as did other globals. The
GFS continues to be the outlier in advertising 0.50 to 0.60"
across a broad area of MN and WI, which is unreasonable given
the speed &evolution of this system, but a narrow region of
higher QPF is still in play per FGEN. Blended guidance is
similar to the 00z ECMWF with a band of 0.20 to 0.30" across
portions of central Minnesota and western Wisconsin. NBM PoPs
have ticked upwards into the 70 to 80% range. This lines up with
higher confidence for precipitation on Thursday.

Here`s a summary: It appears likely that a broad area of snow
will impact the Upper Midwest on Thursday & Thursday night,
with increasing confidence for a few inches of accumulation
despite recent warmth and thawed ground. Specifics with regards
to timing, amounts, placement, intensity, and travel impacts
will come into greater detail as additional guidance becomes
available. If you`re put away your snow shovel or winter gear
it`s not too late to get it back out! You have a few days to
prepare.

Beyond Thursday, our attention turns to next weekend (and early
next week). Guidance suggests a deep trough will dig into the
western CONUS with several shortwaves embedded within the broad
longwave trough. There is a significant amount of uncertainty
with respect to the evolution of this period, but there is
remarkable consistency with the signal for potential of a few
waves of precipitation across the Midwest. The first window is
Saturday into Sunday as a shortwave lifts out of the Rockies and
into the Plains. NBM PoPs are beginning to increase for this
upcoming weekend in response to the stormy signal.
Unfortunately, P-type issues are likely given the potentially
dynamic nature of this system. What`s important is not any one
specific model run, but the consistency in the signal for a
storm. This should support a greater potential for beneficial
precipitation across the region as we end March.

&&

.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 1221 PM CDT Mon Mar 18 2024

The overcast deck of low-VFR stratus has quickly burned off late
this morning with only partial remnants remaining over western
WI. This should also burn off early this afternoon, resulting in
comfortable VFR cigs through most of tonight. CAMs show broken
to overcast skies moving in from the northwest during Tuesday
morning likely resulting in a period of MVFR cigs for most of
the morning hours. Winds become southwesterly at 10-15 knots
this afternoon remaining similar overnight. A period of LLWS
exists for a few hours surrounding midnight tonight. It will
generally be westerly between 40-50 knots. During Tuesday
morning, winds will become northwesterly and increase in speed
with sustained values of 15-20 knots and gusts around 25 knots.

KMSP...Have kept LLWS from 04-08Z tonight with a westerly
direction near 50 knots. MVFR cigs look likely after 12Z Tuesday
morning as an overcast cloud deck near 2700 feet moves overhead.
Conditions should return to VFR by noon Tuesday.

/OUTLOOK FOR KMSP/
WED...VFR. Winds NW 15G25kts.
THU...IFR/-SN likely. Some accumulation likely. Wind E 5-10
kts.
FRI...VFR likely. MVFR ceilings possible. Wind N 5-10 kts.

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
MN...None.
WI...None.

&&

$$

DISCUSSION...BPH
AVIATION...CTG


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